code: def _check_call(self):
      x = _random_array(self.link.xp, (2, 3, 32, 32))
      hs = self.link(x)
  
      self.assertEqual(len(hs), 3)
      for l in range(len(hs)):
          self.assertIsInstance(hs[l], chainer.Variable)
          self.assertIsInstance(hs[l].array, self.link.xp.ndarray)
          self.assertEqual(hs[l].shape, (2, 256, 16 >> l, 16 >> l))
  
file_path: chainercv/tests/links_tests/model_tests/fpn_tests/test_fpn.py
imports: from __future__ import division
  import numpy
  import unittest
  import chainer
  from chainer import testing
  from chainer.testing import attr
  from chainercv.links.model.fpn import FPN
label_desc: Use image node_id 3 for calling the TestFPN obj's underlying member method code with example usage: obj._check_call() without return types